The Animal/Morphology Core B will provide SAMP1/Yit mice for use in each of the individual projects. Maintaining the SAMP1/Yit breeding colony and experimental animals in a common centralized facility under uniform environmental conditions is crucial to the success of the program because of evidence that environmental cofactors such as colonization of the gut with bacteria flora can effect the presence or course of disease. Centralization of animal production will also reduce costs by eliminating redundant breeding colonies, and ultimately reduce the numbers of animals required by ensuring efficient utilization by each of the projects. A second aim is to provide centralized histological services and assistance with immunohistochemistry, digital fluorescence and brightfield microscopy for each of the projects. The third aim of the Animal /Morphology core is to provide centralized histopathological analyses of inflammation and other morphological parameters to investigators within the program. A centralized core component for analysis of the histopathological features of ileitis in this model will provide a common framework for interpretation of data generated by each of the four projects. A strength of this component is the availability of two experienced GI pathologists, Dr. Moskaluk and Dr. Nast, to perform histopathological scoring of samples to each of the projects and to provide ongoing consultative service to the projects concerning the pathological features of disease in this model. The fourth aim is to provide a resource for providing mice with induced mutations on induced mutations into an appropriate background can be accomplished in 3 to 4 generations. Dr. Cohn will direct the core and Dr. Moskaluk will serve as co-director. A committee consisting of the core director, the co-director, and Dr. Cominelli, the PI of the program will address routine quality control and prioritization issues. An oversight committee will review the operation of the core on yearly basis.